Workers in Rangoon, Burma, prepare for an onslaught of news media before President Obama's visit - the first ever by a sitting president. / Gemunu Amarasinghe, AP

by Calum MacLeod, USA TODAY

by Calum MacLeod, USA TODAY

BANGKOK - On his first overseas trip since his re-election, President Obama heads Saturday for the Southeast Asian nations of Thailand, Burma and Cambodia.

He'll meet a much revered king, an army general turned president and a strongman who fought for the murderous Khmer Rouge.

But throughout his whirlwind, four-day tour, another Asian country will loom large. For the trip appears set to reinforce the U.S. "pivot" toward Asia, a strategic shift since 2011 that communist China views as being aimed squarely at countering its influence and containing its growth.

All three countries have close China ties, although Burma, amid dramatic reform away from military dictatorship, has indicated it wants to reduce its dependence on Beijing.

Other Asian nations have complained of China's aggressive stance in several territorial disputes over islands claimed by neighboring countries.

"China must play by the rules," Secretary of State Hillary Rodham Clinton, who will accompany the president, said while visiting Australia.

Many Chinese are concerned about American diplomatic competition for friends around the periphery of China, said Shi Yinhong, an international relations expert at People's University of China in Beijing.

"In recent times, China has not done as well as Obama," Shi said.

That failure stems partly from rising nationalism at home.

"In China, people think 'these are our islands,' so it's a difficult task to strike a balance between foreign policy and strategic requirements, and, on the other hand, domestic requirements, to show people you have guts and will defend our national interests effectively," Shi said.

The presidential visit will "embed the U.S. presence and future power projection in the region in the context of China's rising influence," wrote Kavi Chongkittavorn, a Thai commentator on Southeast Asian affairs, in The Nation newspaper. "It will also turn ASEAN (the Association of Southeast Asian Nations) into an arena where the world's two superpowers can cajole, cooperate and compete."

From Saturday to Sunday, Obama visits Bangkok to meet Thailand's king and its first female prime minister, Yingluck Shinawatra. The country is among America's oldest allies in Asia, but tensions exist, including disagreement over the U.S.-led Trans-Pacific Partnership that Thailand may join, and Thailand's refusal to allow NASA to use an airfield for atmospheric monitoring.

On Monday, Air Force One makes its maiden flight to Rangoon, Burma, also known as Myanmar, to start the first visit by a sitting U.S. president. The White House, which eased trade sanctions in recent months against this once-pariah regime, has come under fire from human rights groups for visiting Burma while ethnic conflicts continue, and rights abuses remain widespread.

Obama will give a speech on democracy and meet both President Thein Sein and Aung San Suu Kyi, the opposition leader and democracy icon who is now a sitting MP, although Burma's parliament remains rigged to ensure the ruling party and military hold sway.

In Rangoon, also known as Yangon, excitement over Obama's visit embraces all levels of society, said Arthur Myint, an editor at The People's Age, a weekly political journal.

"The interest reflects the changes here. People hope Obama will put pressure on the government to make more changes," he said Thursday. "Some political prisoners were released this morning, and people feel it's connected to Obama's visit."

Unease over China's heavy influence, especially in business, is another reason Obama can expect a warm welcome, Myint said.

"Everyone is happy that Myanmar is getting closer to Western nations, especially the United States," he said.

His last leg, Cambodia, also marks a historic first visit by a sitting U.S. president. Obama will share the limelight with world leaders including Russia's Vladimir Putin and China's Wen Jiabao, as Cambodian Prime Minister Hun Sen hosts the annual ASEAN summit and seventh East Asia Summit.

But local interest is centered on Obama, said Sambath Samoeurn, 25, a marketing employee at a Phnom Penh newspaper.

Residents have put up pictures of Obama in their homes and prepared welcome banners, he said. Others are preparing protests.

"Many people here will raise issues, for example about land conflicts; they want to push Obama to take action," he said, noting that heavy security will likely keep protesters far from Obama's view.

Cambodian problems such as land grabs and the rich-poor divide are highly familiar to Premier Wen from a China also riven with inequality, but Beijing's focus will center on the summit's most sensitive topics, maritime security and disputes in the South and East China seas. Washington argues for a multilateral approach and a regional code of conduct, while Beijing insists on bilateral negotiations.